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Platooning is an effective way to reduce air resistance and fuel consumption in vehicular transportation. However, stochastically generated disturbances can significantly impact the string stability of platoons. This article proposes a novel control law, based on sliding mode control and leader‐predecessor communications, designed to improve the exponential mean‐square string stability of platoons with Ito‐type stochastic disturbances that consider friction force. Specifically, our approach employs a third‐order nonlinear dynamic model to capture the relevant spatiotemporal correlations present in vehicle platoons. The proposed longitudinal control strategy effectively stabilizes the platoons with time delay and was verified through simulation experimentation. In this study, the stability of sliding mode motion is thoroughly investigated by means of sub‐reachable and practical stability analysis with sliding mode control. The findings of this study provide a theoretical foundation for further research on vehicle platoons with increasingly complicated interference and time delays. Overall, our results demonstrate that our approach can achieve significant improvements in both fuel economy and exhaust emissions while maintaining high levels of string stability, further contributing to the development of efficient and sustainable transportation systems. [ABSTRACT FROM AUTHOR]

Ceramic nanofibrous sponges are attractive for their broad applications in high-temperature air filtration, thermal insulation, sewage treatment, and catalyst support. However, the present ceramic sponges usually show brittle fracture even under tensile stresses. Herein, a ceramic sponge assembled by ultralong and crimped Si 3 N 4 nanofiber nanofibers is designed and prepared to achieve temperature-invariant reversible from liquid nitrogen to 1200 °C and large elongations (ductile failure over 100 %) as well as excellent compressive anti-puncturing property. Moreover, the ceramic sponge illustrates a high filtration efficiency of 99.6 % for PM 2.5 and a low-pressure drop of 32 Pa during a long-term test under high-speed gas flow. It can also support photocatalyst g-C 3 N 4 nanoparticles, yielding a high efficiency of photodegradation of nitrogen oxide gases. The well-designed ceramic nanofiber sponge with good comprehensive mechanical performances thus shows promising applications in air purification under extreme working conditions. [ABSTRACT FROM AUTHOR]

Gas embolism is a medical condition that occurs when gas bubbles are present in veins or arteries, decreasing blood flow and potentially reducing oxygen delivery to vital organs, such as the brain. Although usually reported as rare, gas embolism can lead to severe neurological damage or death. However, presently, only limited understanding exists regarding the microscale processes leading to the formation, persistence, movement, and resolution of gas emboli, as modulated by microvasculature geometrical features and blood properties. Because gas embolism is initially a physico-chemical-only process, with biological responses starting later, the opportunity exists to fully study the genesis and evolution of gas emboli using in vitro microfluidic networks mimicking small regions of microvasculature. The microfluidics networks used in this study, which aim to mimic microvasculature geometry, comprise linear channels with T-, or Y-junction air inlets, with 20, 40, and 60 μm widths (arterial or venous), and a 30 μm width honeycombed network (arterial) with three bifurcation angles (30°, 60°, and 90°). Synthetic blood, equivalent to 46% haematocrit concentrations, and water were used to study the modulation of gas embolism-like events by liquid viscosity. Our study shows that (i) longer bubbles with lower velocity occur in narrower channels, e.g., with 20 μm width; (ii) the resistance of air bubbles to the flow increases with the higher haematocrit concentration; and lastly (iii) the propensity of gas embolism-like events in honeycomb architectures increases for more acute, e.g., 30°, bifurcation angles. A dimensionless analysis using Euler, Weber, and capillary numbers demarcated the conditions conducive to gas embolism. This work suggests that in vitro experimentation using microfluidic devices with microvascular tissue-like structures could assist medical guidelines and management in preventing and mitigating the effects of gas embolism. [ABSTRACT FROM AUTHOR]

The cooling performance of a centrifuge was enhanced using a perforated windshield. The windshield spatially separates the rotor and the chamber, reducing turbulence and air resistance. On the other hand, during centrifuge rotation, heat is generated by friction between the internal structure and air. Optimizing the windshield shape and facilitating efficient heat exchange with the chamber wall are essential for cooling the sample container inside the windshield. This study examined the cooling performance of the perforated windshield through analysis and experiment. The effects of the presence, location, and diameter of the perforations were compared using computational fluid dynamics (CFD) simulations and considering temperature and flow characteristics. These results suggest that the perforated windshield enhances the cooling performance of the centrifuge. [ABSTRACT FROM AUTHOR]

Understanding both positive and negative impacts of climate change is essential for comprehensively assessing and well adapting to the impacts of changing climate. Conventionally, climate warming is revealed to negatively impact human activities. Here, we reveal that human beings' performance in anaerobic sports may benefit from climate warming. Using global weather observation and athletes' performance datasets, we show that world-top athletes' performances in nearly all athletics anaerobic events (i.e., sprints, jumps and throws) substantially improve as ambient temperature rises. For example, 100 m performance monotonically improves by 0.26 s as ambient temperature rises from 11.8° to 36.4 °C. Using Coupled Model Intercomparison Project Phase 6 datasets, we further show that global warming can substantially improve world-top athletes' performance in eleven of the thirteen Olympics athletics anaerobic events by 0.27%–0.88% and 0.14–0.48% under high-emission and medium-emission scenarios, respectively, during 1979–2100. Among them, the improvements for 100 m are 0.59% (0.063 s) and 0.32% (0.034 s), respectively. Mechanism analysis shows that the warmed ambient atmosphere can improve competitors' performance through expanding the air and thus reducing the air resistance to the competitors and throwing implements for hummer throw and all the sprints, hurdling and jumps. Quantitative analysis estimates that this thermodynamic process is essential for the impacts of warmed ambient atmosphere on the performances in these events as physiological processes are. [ABSTRACT FROM AUTHOR]

Accumulation landslides are prone to occur during the continuous infiltration of heavy rainfall, which seriously threatens the lives and property safety of local residents. In this paper, based on the Green-Ampt (GA) infiltration model, a new slope rainfall infiltration function is derived by combining the effect of air resistance and lateral seepage of saturated zone. Considering that when the soil layer continues to infiltrate after the saturation zone is formed, the air involvement cannot be discharged in time, which delays the infiltration process. Therefore, the influence of air resistance factor in soil pores is added. According to the infiltration characteristics of finite long slope, the lateral seepage of saturated zone is introduced, which makes up for the deficiency that GA model is only applicable to infinite long slope. Finally, based on the seepage characteristics of the previous analysis, the overall shear strength criterion is used to evaluate the stability of the slope. The results show that the safety factor decreases slowly with the increase of size and is inversely correlated with the slope angle and initial moisture content. The time of infiltration at the same depth increases with the increase of size and slope angle, and is inversely correlated with the initial moisture content, but is less affected by rainfall intensity. By comparing with the results of experimental data and other methods, the results of the proposed method are more consistent with the experimental results than other methods. [ABSTRACT FROM AUTHOR]

In high-speed motors, there is a huge amount of heat generation from core and winding losses, which may result in thermal failures or motor performance deterioration. In the prevention of heat accumulation, efficient cooling technology is critical for smooth and reliable motor movement. This paper summarizes the diverse application of high-speed motor and thermal requirements, such as in electrical devices, turbo-machinery, and high-precision machine tools. Three paths of case convection—cooling, internal ventilation cooling and spindle core cooling—are analyzed. Methods for configuring thermal resistance and improving cooling efficiency are summarized. Among them, coolant flow characteristics and flow channel shapes, gas supply ventilation systems, and methods to reduce air resistance, as well as axial cooling and integrated heat pipe structures, are extensively investigated. Finally, the development prospects of high-speed motor cooling are also forecasted. At present, the primary research directions are to reduce the heat generated by the heat source, utilize the latent heat of the coolant, optimize the cooling flow path of the shell, design an axial air-cooling circulation system, and enhance the heat dissipation of the spindle. [ABSTRACT FROM AUTHOR]

A key component of a Solid Oxide Fuel Cell (SOFC) is the interconnect, which connects individual fuel cells in series to form a fuel cell stack. The interconnect is exposed to air and fuel in parallel; these so-called dual-atmosphere conditions cause severe corrosion on the air-side. This work investigates interconnect coatings that can mitigate this effect. Physical Vapour Deposition (PVD) coatings of Cr 2 O 3 , CeO 2 , YSZ, and Al 2 O 3 on ferritic stainless steel (AISI 441) were exposed under dual-atmosphere conditions for up to 3000 h. The evolution of the corrosion products was evaluated using optical microscopy and Scanning Electron Microscopy (SEM) in combination with Energy-dispersive x-ray Spectroscopy (EDS). The SEM analysis showed that a chromia coating was not sufficient to reduce the dual-atmosphere effect, while other coatings on the fuel-side suppressed the dual-atmosphere effect by forming a barrier to hydrogen permeation. The best outcomes were observed with Al 2 O 3 coatings on the fuel-side, which drastically reduced the dual-atmosphere effect. A 30 nm Al 2 O 3 coating displayed acceptable Area-Specific Resistance (ASR). • Fuel side PVD coatings as barriers against hydrogen ingress are investigated. • Coatings can significantly improve the corrosion resistance on the air side. • A CeO 2 coating has good conductivity and provides acceptable corrosion protection. • A 30 nm Al 2 O 3 layer provides good barrier properties and acceptable ASR. [ABSTRACT FROM AUTHOR]

We formulate a phenomenological model to study the power applied by a cyclist on a velodrome—for individual timetrials—taking into account the straights, circular arcs, connecting transition curves, and banking. The dissipative forces we consider are air resistance, rolling resistance, lateral friction and drivetrain resistance. Also, in general, the power is used to increase the kinetic and potential energy. However, to model a steady ride—as expected for individual timetrials—we assume a constant centre-of-mass speed and allow the cadence and power to vary during a lap. Hence, the only mechanical energy to consider is the increase of potential energy due to raising the centre of mass upon exiting each curve. Following derivations and justifications of expressions that constitute this mathematical model, we present a numerical example. We show that, as expected, the cadence and power vary only slightly during a steady ride. In addition, we examine changes in the required average power per lap due to modifications of various quantities, such as air density at a velodrome, laptime and several others. Such an examination is of immediate use in strategizing the performance for individual pursuits and the Hour Record. [ABSTRACT FROM AUTHOR]

Installing a precooler behind the intake is an effective approach for hypersonic air-breathing pre-cooled engine to cool the hot incoming air. Synergetic airbreathing rocket engine is a revolutionary hypersonic air-breathing pre-cooled engine with complex thermodynamic cycle i.e. air cycle, helium cycle. Air/helium precooler is a key component and its configuration and operating condition have great effect on the performance characteristics of air-breathing pre-cooled engine. Thus, the minimum periodic flow and heat transfer model of the precooler are established. The effects of key parameters on the heat transfer performance of precooler are numerically studied. The results indicate that: when the tube row number increases from 7 to 15, the average heat transfer coefficient of air side decreases by 57%, the heat exchange rate increases by 19%, and effectiveness increases by 18.4%. The tube transverse pitch can enhance the heat transfer coefficient of air and helium side, while the heat exchange rate decreases by 33 % when the tube transverse pitch increases from 1.5 to 3.5. The helium inlet velocity can improve the heat transfer performance of precooler and reduce the flow resistance of air side. [ABSTRACT FROM AUTHOR]

Air salinity is one of the problems for horticulture production in coastal areas. Cabbage and Cauliflower are horticulture commodities that have the potential to develop in coastal areas. The present study aimed to examine the agro-physiological response of cabbage (Brassica oleracea var. capitata) and cauliflower (B. oleracea var. botrytis) to different concentrations of air salinity. This research was a factorial experiment on polybags arranged according to a completely randomized block design with two factors. The first factor was the crop type, namely cabbage (Grand 22) and cauliflower (Larissa F1). The second factor was the concentration of air salinity, namely 0 dS. m-1, 6 dS. m-1, 12 dS. m-1, and 18 dS. m-1. The agro-physiological changes studied were crop yield, leaf chlorophyll content, stomata density, and proline content. A stress tolerance index was measured to determine the level of crop resistance to air salinity stress. The results explained that air salinity was not able to affect crop growth and yield, but it enabled to affect crops physiologically. The highest decrease in leaf chlorophyll content was at 18 dS. m-1 of 29.16% in the vegetative stage and 37.88% in the generative stage. There was an increase in proline accumulation of leaf (1,320.63%) when the air salinity was increased (18 dS. m-1). However, the accumulation of cabbage proline was lower than that of cauliflower. Based on the stress tolerance index, cabbage is included in the category of tolerant, while cauliflower is in the category of moderate tolerance to air salinity. [ABSTRACT FROM AUTHOR]

The article discusses the development of an unmanned aerial-aquatic vehicle system called TJ-FlyingFish. The system is designed to maneuver effectively in both water and air, utilizing a dual-speed and tilting propulsion units for thrust and agility. A multi-sensor-based localization system supports seamless transitions between aerial and aquatic environments. The article presents the design, control scheme, and experimental results of the TJ-FlyingFish system. The text also discusses challenges in localization, dynamics modeling, and control design, as well as the performance of the propulsion units. Ongoing efforts are focused on improving algorithm and structure design for better performance. [Extracted from the article]

The study of insect flight is important for conservation and sustainability efforts, as predicting insect dispersal can aid management programmes in tackling economic and ecological harm from, for example, invasive species. Flight mills are invaluable tools for measuring the factors of insect flight under laboratory conditions, as they lower several technical and financial barriers to conduct experiments. It is especially difficult, however, to make assumptions about the energetic cost of tethered flights conducted using different tethers, or even on different flight mills, due to the mechanical variability of the bearing friction and air resistance of the rotating assembly. This additional uncertainty necessitates a larger number of replicates for any given standard of statistical confidence. By characterising flight mill friction, this uncertainty can both be reduced in magnitude and assigned a specific, well‐defined numerical value. We present a simple methodology to characterise this friction through dynamic calibration of the flight mill, at a high statistical confidence. This study uses videography of a flight mill undergoing free velocity decay due to friction, using an in‐house developed software to extract angular velocity from video data. However, the technique is readily adaptable to other measurement techniques. Using the velocity, alongside the mass moment of inertia of the flight mill, allows us to determine the rotational friction coefficient. This friction coefficient provides precise measurements of thrust production, and therefore the energy expenditure of flight, by the tethered insect. [ABSTRACT FROM AUTHOR]

This paper explains the detailed design and implementation process of a solar car. The design of the proposed solar car system represents a broader perspective than that of traditional solar or electric cars. It can be regarded as a hybrid vehicle that integrates solar power as a fundamental aspect of its performance, while also offering the option of direct plug-in charging. The proposed solar-powered four-wheeled car uses two motors to increase the efficiency of power consumption, as both motors generate a relatively high torque and power ratio. The design of the car considers aerodynamics. The solar panel placement has a unique geometric shape that reduces air resistance, thus increasing efficiency and stability on the road. To increase the total rated power to 810 W, six panels were installed on top of the car. Each panel is capable of producing 135 W with an efficiency of 23%. In addition, the car features two identical motor controllers paired with adjacent motors, which contributes to a rear-wheel-drive experience. To safeguard the motor controllers, the system includes protective elements such as an in-line fuse, which is directly connected to the battery. The conducted testing of the implemented car validates the successful and adaptable design, offering promising prospects for an efficient commercial prototype of a solar car. [ABSTRACT FROM AUTHOR]

The loading and unloading elevators are the primary equipment in the refueling system, used for transferring fuel assemblies in the sodium-cooled fast reactors. The guideway friction pairs are the critical components of these elevators in the refueling system. With the excellent hardness and wear resistance in air, nitrided W18Cr4V steel is a promising material for the guideway friction pairs. In order to assess the feasibility of using nitrided W18Cr4V steel, it is essential to understand the aging behavior of nitrided W18Cr4V steel in high-temperature sodium. Aging tests were conducted on nitrided W18Cr4V steel in sodium and in argon environments at various temperatures for different exposure times. The results showed that the nitrogen atoms in the nitrided layer exhibited bidirectional diffusion behavior in the sodium or argon environment at 540 °C. Compared to the argon environment, cracks formed within the nitrided layer and the diffusion of nitrogen into the sodium was accelerated in the nitrided layer. As a significant number of nitrogen atoms had diffused into the sodium, there was little difference in the hardness between nitrided W18Cr4V steel and non-nitrided W18Cr4V steel after long-term exposure to 540 °C sodium. [ABSTRACT FROM AUTHOR]

Long-term exposure to high concentrations of fine particulate matter (PM2.5) in the atmosphere has negative impact on the long-term health effect of human beings. Traditional air filtration materials are difficult to take into account the high-efficiency and low-resistance protection, and are non-degradable, which not only aggravates global plastic pollution, but also tends to cause stronger microplastics hazards. To solve the problems above-mentioned, self-powered and biodegradable nanofibrous membranes with air slip effect are developed to achieve a long-term and low-resistance respiratory protection. A two-step hydrothermal method is proposed to prepare the easily dispersed BTO dielectric with an average particle size of 49.6 nm, then the BTO nanoparticles (BTO NPs) are embedded into the PLA nanofibrous membranes by a combined “electrospinning‒electrospray” strategy. The frictional electricity effect and size effect of BTO NPs are utilized to simultaneously regulate the filtration efficiency and resistance of nanofibrous membranes. By controlling the concentration of BTO NPs in spraying suspension, the relationship between it and electroactivity, filtration properties and mechanical properties of PLA/BTO nanofibrous membranes is investigated. Microstructure characterization and performance testing show that the PLA/BTO nanofibrous membranes have excellent electroactivity, filtration properties and mechanical properties. The surface potential of PLA/BTO nanofibrous membranes is up to 5.9 kV, the dielectric constant is up to 1.20 F/m, and the average output voltage is up to 12.4 V. Benefiting from the enhanced slip effect and increased electroactivity, the electrospun-electrosprayed PLA/BTO10 nanofibrous membrane could significantly reduce air resistance (as low as 20 Pa), while improving the filtration efficiency of PM0.3 by 7.78%−9.05% and the filtration efficiency of PM2.5 by 2.90%−13.19%. Even at the high airflow velocity of 85 L/min, the filtration efficiency of PM2.5 still achieves as high as 97.25%. At the same time, the increase of tensile strength of PLA/BTO nanofibrous membranes is up to 60% (22.5 MPa), the increase of elongation at break is up to 68% (25%), and the fracture toughness increases by 1.3 times (3.6 MJ/m3). Therefore, the proposed degradable PLA/BTO nanofibrous membrane filters with long-term and low-resistance filtration properties have some broad application prospects in the field of respiratory protection, and also provide a new approach to alleviate the plastic pollution exacerbated by discarded masks.

Since the dead-zone fault in substations often has a relatively long removal time, it may damage the insulation of power equipment and even threaten the stability of the power system. In this paper, the movement of the dead-zone fault electric arc in a 220-kV substation is investigated. The arc chain model for the dead-zone fault electric arc is developed; the influences of electromagnetic force, thermal buoyancy, and the air resistance stressed on the electric arc are comprehensively considered. The electric arc velocity and displacement are computed. Then, the spreading characteristics of the dead-zone electric arc under various conditions are studied. The spreading trend of the dead-zone fault electric arc is summarized. Finally, measures to inhibit the spreading of the electric arc are suggested. The study indicates that the movement of the electric arc in the dead zone during the early stage is primarily influenced by the electromagnetic force resulting from the overpass and conductor, and the arc is concave and has an irregular trajectory. The inclination angle of the conductor significantly affects the direction of the electromagnetic force. If the conductor is laid horizontally, the electric arc is subjected to a smaller force. The electromagnetic force stressed on the electric arc is mainly attributed to the fault phase conductor and the electric arc body itself, whereas those from the other phase conductors are minor. The initial position of the arc root has a certain impact on the movement of the electric arc. The use of the insulating materials restricts the arc root movement. [ABSTRACT FROM AUTHOR]

Highly permeable particulate matter (PM) can carry various bacteria, viruses and toxics and pose a serious threat to public health. Nevertheless, current respirators typically sacrifice their thickness and base weight for high-performance filtration, which inevitably causes wearing discomfort and significant consumption of raw materials. Here, we show a facile yet massive splitting eletrospinning strategy to prepare an ultrathin, ultralight and radiative cooling dual-scale fiber membrane with about 80% infrared transmittance for high-protective, comfortable and sustainable air filter. By tailoring antibacterial surfactant-triggered splitting of charged jets, the dual-scale fibrous filter consisting of continuous nanofibers (44 ± 12 nm) and submicron-fibers (159 ± 32 nm) is formed. It presents ultralow thickness (1.49 μm) and base weight (0.57 g m−2) but superior protective performances (about 99.95% PM0.3 removal, durable antibacterial ability) and wearing comfort of low air resistance, high heat dissipation and moisture permeability. Moreover, the ultralight filter can save over 97% polymers than commercial N95 respirator, enabling itself to be sustainable and economical. This work paves the way for designing advanced and sustainable protective materials. Development of high-performance, comfortable and sustainable air filters is challenging. Here, authors design an ultrathin, ultralight dual scale fiber mat composed of true nanofibers and submicron-fibers to integrate the high protection, thermal wet comfort and save raw materials. [ABSTRACT FROM AUTHOR]

This study delves into the intricate dynamics of laser-induced damage in fused silica using a time-resolved pump-probe (TRPP) shadowgraph. Three typical ultra-fast processes, laser-induced plasma evolution, shockwave propagation and material fracture splashing, were quantitatively investigated. The results indicate that the diameter of plasma is proportional to the pulse laser energy and increases linearly during the pulse laser duration with an expansion rate of approximately 6 km/s. The maximum shockwave velocity on the air side is 9 km/s, occurring at the end of the pulse duration, and then rapidly decreases due to air resistance, reaching approximately 1 km/s around a 300 ns delay. After hundreds of nanoseconds, there is a distinct particle splashing phenomenon, with the splashing particle speed distribution ranging from 0.15 km/s to 2.0 km/s. The particle sizes of the splashing particles range from 4 μm to 15 μm. Additionally, the smaller the delay, the faster the speed of the splashing particles. Overall, TRPP technology provides crucial insights into the temporal evolution of laser-induced damage in fused silica, contributing to a comprehensive understanding essential for optimizing the performance and safety of laser systems. [ABSTRACT FROM AUTHOR]

The inherent high thermal resistance of air impedes the heat transfer rate from tube surfaces to airflow within channels. This study aims to mitigate this issue by deploying perforated convex delta winglet pairs as vortex generators (VGs), strategically arranged in-line to reduce thermal resistance. Experimentation involved the installation of these vortex generators within the test section of a rectangular channel. Both convex delta winglet and perforated convex delta winglet pairs were mounted onto a flat plate in configurations of one, two, and three pairs. Airflow velocity within the channel was varied from 0.4 to 2.0 m/s at intervals of 0.2 m/s. Findings demonstrate an increase in the Nusselt number ratio by 1.5 and a 1.4 increment in the friction factor ratio with the utilization of three-row convex delta winglet pairs (CxDWPs) VGs at a Reynolds number of 8,724. Consequently, the thermal-hydraulic performance (TEF) approached a value of nearly 1.3 through the application of convex delta winglet vortex generators. This enhancement signifies the efficacy of convex delta winglets in augmenting heat transfer, thus addressing the challenge posed by air's thermal resistance. [ABSTRACT FROM AUTHOR]

The air pressure resistance experienced by an automotive door during its closing process significantly affects user experience. However, owing to the motion complexity of sliding doors, their aerodynamic behavior during closing has not been investigated. In this study, a fluid–solid coupled simulation approach is proposed, in which data exchange between multibody dynamics simulation and computational fluid dynamics simulation is achieved via the functional mockup interface protocol. Actual vehicle tests are conducted to validate the coupled simulation approach, and the results show an average error of 5.2% for the maximum air pressure in the cabin during door-closing. Investigations into the aerodynamic behavior show that the air pressure distribution inside the cabin remains highly uniform throughout the door-closing process and that a significant correlation exists between the air pressure variation and sliding door motion. The effects of the motion mechanism parameters of the sliding door on air pressure are analyzed. A positive correlation is indicated between the air pressure and middle rail radius. When the radius increases from 60 to 120 mm, the maximum air pressure increases by 13.6%. Positive correlations are indicated between the air pressure and the offsets of the hinge of the middle arm along the x- and y-directions. When the hinge's offset is changed from −10 to 10 mm along the x- and y-directions, the maximum air pressure increases by 5.5% and 8.9%, respectively. [ABSTRACT FROM AUTHOR]

In order to improve the deep ventilation conditions at Fankou Lead - Zinc Mine, the air volume and resistance were measured and the air volume demand was calculated. The total air inlet and return of the deep ventilation system were 330. 38 m³/s and 345.95 m³/s, respectively. The total air resistance in the deep panel is 0.012 3 N. s²/m³. In order to solve the problems of unreasonable distribution of air volume, lengthy ventilation lines, and high resistance among deep levels and working faces, 4 optimization schemes are proposed and simulated in 3D. The results show that the optimization and transformation of the deep ventilation system should choose the scheme of "adding air inlet and return shafts & setting multi-stage ventilators", which can not only realize on-demand air flow in different levels and stopes. It can also increase the air volume that enters each level and sublevel stope to meet future production needs. [ABSTRACT FROM AUTHOR]

This article presents the findings of two experiments that measured the acceleration of a ball rolling down a V-shaped channel. Despite using different release and timing methods, the experiments yielded similar results. The article also examines the disparities between Galileo's description of the experiment and the actual setup, particularly regarding the groove's depth. The results indicate that velocity changes in equal time intervals, and displacement increases as the square of the time taken. The article concludes by discussing the implications of rolling and rectilinear motion on the experiment and emphasizes the significance of precise measurement techniques and manual skills. In another experiment, the article compares manual and mechanical timing methods for measuring the descent of balls down an inclined plane. The results show that both methods produced similar outcomes, with a slight discrepancy between theoretical and experimental data. The article suggests that factors like surface roughness and ball imperfections may contribute to these discrepancies. Overall, the experiment underscores the importance of accurate measurement techniques and the complexities of real-world motion. [Extracted from the article]

This study details the development and validation of a graphene-based ice detection system, designed to enhance flight safety by monitoring ice accumulation on aircraft surfaces. The system employs a semiconductive polymer (PEDOT:PSS) with graphene electrodes, interpreting resistance changes to detect water impact and ice formation in real time. The sensor's performance was rigorously tested in a wind tunnel under various temperature and airflow conditions, focusing on resistance signal dependency on air temperature and phase change. The results demonstrate the sensor's ability to distinguish water droplet impacts from ice formation, with a notable correlation between resistance signal amplitude and water droplet impacts leading to ice accretion. Further analysis shows a significant relationship between air temperature and the resistance signal amplitude, particularly at lower temperatures beneficial to ice formation. This underlines the sensor's precision in varied atmospheric conditions. The system's compact design and accurate detection highlight its potential for improving aircraft ice monitoring, offering a path toward a robust and reliable ice detection system. [ABSTRACT FROM AUTHOR]

This study presents a specialized mixer design for gas burners aimed at improving the efficiency of phase mixing while minimizing system resistance and energy consumption. The proposed design utilizes a multi‐cavity mixer employing both radial and axial mixing techniques, eliminating the need for additional power supply. Full premixed combustion of small gas‐fired industrial boiler has the function of "inhibiting" NOx emission from the source, and good mixing of fuel and combustion supporting air in the early stage is the primary prerequisite for realizing full premixed combustion denitration. In this article, a radial multichamber static mixer is designed following the characteristics of full premixed mixing in gas‐fired industrial boilers. The results demonstrate that the maximum pressure drop of the static mixer is 806 Pa; for gas and air branch pipes, the resistance coefficient f decreases rapidly with the increase in Reynolds number; when Re ≥ 1.2 × 103, the resistance coefficient in the air branch pipe decreases slowly; when Re ≥ 4.5 × 103, the resistance coefficient of gas branch pipe decreases slowly. Additionally, the maximum calculation error of symmetrical gas branch pipe is 9.1%. The static mixer's inlet exhibits a converted velocity of 24 m/s, and the outlet demonstrates an airflow velocity of 23.2 m/s. As a result, a kinetic energy loss of 6.5% is observed. The static mixing chamber makes the airflow rotate and causes different gases to shear and mix. The mixing channel has the function of correcting the airflow deviation, especially for the sudden expansion section. Generally, the two gases can be mixed evenly at the outlet of the mixer. The standard k‐e model and realizable k‐e model are employed to simulate the sudden expansion channel, and indicate that the standard k‐e has a wider range of influence. Further investigation is recommended to better comprehend and optimize this particular area of influence. [ABSTRACT FROM AUTHOR]

The paper proposes an original one-stage method using spark plasma sintering technology (SPS) of manufacturing the ionizing radiation source (IRS) of closed type with a non-dispersible ceramic core based on pollucite obtained using aluminosilicate raw materials saturated (24.3 wt%) with cesium, and doped with 10–40 wt% CsCl. According to the XRD, EDX, AAS and DTA-TG data, optimal conditions for hydrothermal synthesis zeolite NaA were established, the consolidation kinetics and phase transformations into ceramic pollucite under SPS conditions were studied. The ceramics had a relative density of 99.8 % and mechanical strength up to 732 MPa, a low rate of cesium leaching 10−7 g/cm2 day and thermal resistance in air up to 1000 °C. It was confirmed by SEM and EDX that the destruction and deformation of pollucite ceramics in the composition with CsCl and steel at the boundary of their contact in the design of the IRS product was absent and diffusion of cesium outside the ceramics did not occur. The achieved cesium content in the ceramic core of the resulting the ionizing radiation source, which meets high quality and regulatory requirements, is 44.3 wt%. The results of the study may be promising for the manufacture of industrial products. [ABSTRACT FROM AUTHOR]

Hemp hurd fiber, a low-value waste stream from the hemp industry, has potential downstream applications as an alternative to non-renewable plastics for single-use food service ware and packaging applications. Packaging paper substrates made from chemically pulped hemp hurd, mixed in varying ratios with bleached thermomechanical radiata pine pulp were developed and tested. Handsheets were characterized using several mechanical property tests including tensile strength, tearing resistance, burst strength, short-span compression, ring crush, together with Gurley air resistance, contact angle, and Cobb60 tests. Generally, addition of hemp hurd fibers significantly improved handsheet mechanical properties. Hot-pressing of the handsheets so as to approximate molded fiber thermoforming further enhanced their performance, with pure hemp hurd handsheets having the highest mechanical properties and barrier performance. A prototype was successfully thermoformed from hemp fiber, demonstrating overall feasibility of this fibre source for molded fibre objects. [ABSTRACT FROM AUTHOR]

In recent years, superhydrophobic surfaces have attracted significant attention due to their promising applications, especially in ice prevention, reduction in air resistance, and self-cleaning. This study utilizes femtosecond laser processing technology to prepare different surface microstructures on polytetrafluoroethylene (PTFE) surfaces. Through experiments, it investigates the relationship between the solid–liquid contact ratio and surface hydrophobicity. The shape of water droplets on different microstructure surfaces is simulated using ANSYS, and the relationship between surface microstructures and hydrophobicity is explored in the theoretical model. A superhydrophobic surface with a contact angle of up to 166° was obtained by machining grooves with different spacings in polytetrafluoroethylene sheets with femtosecond laser technology. Due to the micro- and nanostructures on the surface, the oleophobicity of the processed oleophilic PTFE surface is enhanced. [ABSTRACT FROM AUTHOR]

SiC preforms were infiltrated with polycarbosiloxane preceramic polymer to create low‐cost SiC—SixOyCz matrix composites for possible high temperature application. The effect of specimen annealing conditions on the steam and air oxidation resistance was analyzed. Air exposures from 900–1500°C showed stability of the SixOyCz matrix phase with moderate oxidation resistance. After 900°C exposures, oxidation of the composite is primarily limited to the matrix phase, and only at 1200 and 1500°C was SiC consumption visualized. Steam cycle exposures at 1200°C resulted in rapid linear oxidation of the composites with induced specimen swelling from volume expansion associated with internal oxidation. Specimens annealed in argon were found to be the most oxidation resistant due to increased matrix crystallinity and carbon retention. The results of this work were used to develop clear strategies for improving the high‐temperature properties of SiC—SixOyCz composites. [ABSTRACT FROM AUTHOR]

Previous studies showed some transition metal high-entropy alloy (HEA) compositions can have good oxidation resistance in air up to 800 °C. Four equiatomic HEAs have been developed based on FeCoCrNi with additions of Mn, Cu, Al or Al+Cu. The oxidation behavior of these HEAs was compared in humid (10 vol.% H2O) air at 800 °C for 100–500 h to investigate the influence of water vapor on the oxidation mechanisms. The Cu- and Al-containing alloys exhibited improved oxidation resistance over the Mn composition. For the Cu-containing alloy, a local attack of the Cu-rich phase was observed, which formed an Fe/Ni/Co/Cr spinel that was surrounded by Cr2O3. This oxide was thicker for the humid air atmosphere when compared to dry air, and the transition of the Cu oxide to the spinel was accelerated. The Al-containing HEA formed a thin Al2O3 scale with humidity suppressing AlN formation and forming a smoother oxide layer. The Al+Cu composition had the highest overall oxidation resistance (minimal local attack, no nitridation) and also showed a smooth oxide scale topography under humid air oxidation as opposed to a plate-like, rougher scale under dry air. [ABSTRACT FROM AUTHOR]

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Purpose: The purpose of this study is to investigate the mechanical properties of denim fabrics constructed from ring-spun and open-end rotor spun yarns. Design/methodology/approach: Yarns of 10s Ne count using cotton fibers were spun using the ring and open-end rotor spinning technologies. The yarns were used to produce a denim fabric on an air-jet loom with a 3/1 twill weave structure. Mechanical tests – tensile strength, tear strength, abrasion resistance and pilling resistance – of denim fabrics were evaluated. The test results were analyzed using analysis of variance with the help of Software Package for Social Sciences. Findings: Denim fabrics made by using ring-spun yarns exhibited better tensile and tear strength properties than denim fabrics made by using open-end rotor spun yarns. On the contrary, denim produced using open-end rotor yarns have better abrasion resistance, pilling resistance and air permeability than those produced using ring-spun yarns. Originality/value: Both spinning techniques have a significant influence on the properties of denim fabrics. Whenever better tensile and tear strength is required, it is better to use ring-spun yarns, while if the requirement is better abrasion resistance and pilling resistance with high air permeability, then open-end rotor spun yarns shall be used. [ABSTRACT FROM AUTHOR]

Purpose: The policy of sustainable development places requirements on businesses to reduce their negative environmental impact. One of the sectors of the economy that is responsible for greenhouse gas emissions is road transportation. Consideration of the European Union9s environmental goals is forcing road carriers to have environmental measures built into their business models. The purpose of the study was to learn how road carriers can reduce their negative environmental impact so that they can fit in with the goals of the environmental policy and to learn about the regulatory tools that the road carriers expect to be able to support these activities. Design/methodology/approach: Data for this study was collected in computer-assisted telephone interviews (CATI). The study was conducted in late 2021 and early 2022 by a Polish company that was responsible for the selection of the sample and the collection of the data. The survey was conducted on a sample of 146 medium and large Polish road freight carriers and was a continuation of a study carried out on the same sample of entities conducted in late 2019 and early 2020 using the same technique. Findings: As part of their fleet policy, in order to fit in with environmental goals, carriers base their business models on the purchase of new means of transportation that meet increasingly stringent emission standards and reinforce environmentally friendly attitudes by buying means of transportation with smaller engine displacement that is tailored to the needs arising from their operations. Pro-environmental operational activities of medium and large Polish road freight carriers involve the use of solutions that change the composition of exhaust gases (AdBlue) and reduce fuel consumption (lowering rolling resistance 3 energy-efficient tires and lowering air resistance 3 fairings), and the acquisition of pro-environmental driving skills (eco-driving). Other environmentally friendly measures are to increase the utilisation of the vehicle capacity (cargo consolidation) and to eliminate empty runs by looking for cargo to be carried on the way back and using route planning software. Originality/value: The paper indicates the methods to reduce the negative environmental impact considered in the business models of medium and large road freight carriers, so that they fit in with the environmental policy goals, and indicates their expectations associated with the support for the achievement of zero-emission transportation. The results can be useful in the adoption on both the European and Polish level of policies leading to a zero-carbon economy. [ABSTRACT FROM AUTHOR]

A diabetes sensor was developed to detect low concentrations of acetone gas, which is a diabetes biomarker. A WO3 nanoneedle film was synthesized via an aqueous process for use as a sensitive sensing membrane. Acetone was adsorbed and oxidized on the WO3 nanoneedle film, which changed the sensor resistance. The sensor exhibited a high response of Ra/Rg = 19.72, where Ra is the sensor resistance in air, and Rg is the sensor resistance in air containing 10 ppmv acetone gas. The sensor also exhibited a high response (25.36) to 1 ppmv NO2, which is related to asthma. Furthermore, the sensor responded to various biogases associated with diseases. The sensor responses to 10 ppmv of the lung cancer marker gases acetaldehyde and toluene were 13.54 and 9.49, respectively. The sensor responses to 10 ppmv isoprene, ethanol, para-xylene, hydrogen, and NH3 were 7.93, 6.33, 4.51, 2.08, and 0.90, respectively. Trace amounts of acetone and NO2 gases (25 and 250 ppbv, respectively) were detected. The limits of detection for acetone and NO2 gases were estimated to be 2.4 and 1.5 ppbv, respectively. The sensor exhibited superior ability to detect low concentrations of biomarker gases. The unique characteristics of the WO3 nanoneedle film contributed to its high response rates. A WO3 nanoneedle film was developed for a gas sensor to detect low concentrations of acetone gas, which is a diabetes biomarker. The sensor exhibited a high response (19.72) to 10 ppmv acetone gas. The sensor also exhibited a high response (25.36) to 1 ppmv NO2, which is related to asthma. The limits of detection for acetone and NO2 gases were estimated to be 2.4 and 1.5 ppbv, respectively. The sensor exhibited superior ability to detect low concentrations of biomarker gases. The unique characteristics of the WO3 nanoneedle film contributed to its high response rates. [ABSTRACT FROM AUTHOR]

In this study, we conducted experiments to explore the potential of a low-power exploding foil initiator for accelerating microparticles through high-speed membrane deformation. This involved the use of a conductive layer with a conversion section known as a "bridge," which was positioned between the substrate and the cover layer. The application of pulsed electrical energy led to Joule heating at the bridge, while the vaporized gas generated impulsive loading, resulting in the deformation of the cover layer. According to the principles of energy conservation, 8.7% of the electrical input energy was converted into kinetic energy for the membrane. This deformation process achieved a velocity of 800 m/s, with a corresponding strain rate of 1.6 × 107 s−1. The applied impulse predominantly induced extension stresses in the cover layer rather than bending stresses. Under these conditions, a 17.5-µm radius polylactic acid bead was propelled and subsequently captured by a silicone gel layer, resembling human dermic skin. Considering factors such as particle clustering and deceleration due to air resistance during supersonic flight, assuming a normal incident angle, it was estimated that approximately half of the ejected particles could reach the human dermic layer, located 200 µm beneath the skin surface. These findings suggest that pulse discharge is a promising method for inducing high-speed membrane deformation, and the electrical microparticle accelerator holds potential for applications in needle-free drug delivery. [ABSTRACT FROM AUTHOR]

Poor fuel–air mixing of the diesel spray in low ambient temperature and pressure or thin air leads to intricate fuel breakup mechanism near the nozzle, which still remains worth of study. In this study, a pressure-based modified multiphase lattice Boltzmann flux solver (MLBFS) is proposed to accommodate the fuel spray breakup characteristics of multiphase, multicomponent, and large density ratio, in which the source terms of governing equation are modified emphatically for high injection pressure. Therefore, the characteristics of microscopic diesel spray breakup induced by Rayleigh–Taylor instability are investigated, including spray penetration, spray area, and spray arc length. It is revealed that the spray penetration is increased exponentially with the fuel–air density ratio Rρ. Influenced by air resistance and circulation interference, the roll-up vortex, droplet size, and spray area increase with the decreasing of Rρ (corresponding to high ambient pressure). Affected by entrainment and Rayleigh–Taylor instability, the development of the spray arc length experienced three stages: rapid growth, peak, and violent fluctuation, in which the lower Rρ facilitates development. It is concluded that Rayleigh–Taylor instability is favorable for stimulating the spray internal circulation of spray to enhance entrainment with surrounding air, while improving roll-up and breakup in the spray tail region. Such investigation is conductive to better understanding the micro-breakup mechanisms of fuel spray in the spray-induced internal combustion engine. [ABSTRACT FROM AUTHOR]

An antimicrobial nanofiber membrane with high efficiency and low resistance for air filtration was prepared using the natural antimicrobial properties of chitosan (CS). To enhance the spinnability performance of CS, CS was treated with alkali to reduce its viscosity. CS/PVA nanofiber membranes were obtained by electrospinning technique using alkali-treated CS and polyvinyl alcohol (PVA) as raw materials. The filtration performance, antibacterial performance and oil-water separation of the CS/PVA fiber membranes were tested. The results show that the chemical structure of CS is not changed after alkali treatment, and the viscosity of CS solution decreases with the increase of alkali treatment time. When the alkali treatment time of CS is 12 h, the CS/PVA fiber membranes are obtained with high filtration efficiency (99.93%) and low filtration resistance (77 Pa), and shows good antimicrobial performance with more than 50% inhibition rate of Staphylococcus aureus. The CS/PVA fiber membrane was then applied to oil-water separation. In the oil-water system, the separation efficiency of the fiber membrane is 99.19%, 99.81% and 99.90% for edible oil, paraffin oil and n-heptane, respectively, and 90.82% for lubricating oil, and the oil-water separation efficiency remains more than 96% after 5 oil-water separation cycles. [ABSTRACT FROM AUTHOR]

Composites based on mineral binders are highly concentrated polydisperse systems. These systems consist of a dispersed phase in the form of particles of filler and binder, hydration products, as well as a dispersion medium in the form of a porous electrolyte (mixing water). The properties of such systems are determined by the action of forces that manifest themselves in interfacial interactions and act within each phase between atoms, ions, or molecules. To increase the strength and water resistance of materials, it is necessary to ensure the formation of contacts in which electrostatic attraction with the maximum interaction energy is realized. A significant role is played by the electric charges and potentials of the surface of the particles of the components of the structure. The introduction of chemical additives provides the synthesis of additional crystalline hydrates with certain surface properties, which contributes to an increase in the number of electroheterogeneous contacts in the system. The introduction of polydisperse mineral fillers, taking into account their surface charges, ensures the formation of a dense structure of a composite material with a large number of electroheterogeneous contacts. Based on the research results, composite materials based on mineral binders of various functional purposes with specified physical‐mechanical, hydrophysical, electrophysical properties have been developed. The use of these materials made it possible to increase the reliability and durability of building structures. [ABSTRACT FROM AUTHOR]

In this work, Fe64Nb3B17Si6Cr6Ni4 and Fe60Nb3B17Si6Cr6Ni4Mo4 (at. %) coatings were prepared with a high-velocity air fuel spraying method, and the effects of minor Mo addition on the microstructure, glass formation, and corrosion resistance of the coating were studied. It was found that the Mo addition improves the glass-forming ability of the alloy and a fully amorphous structure with a higher compactness was obtained in the Mo-containing coating. The thermal stability of the coating is enhanced by Mo addition and the onset crystallization temperature was increased by 20 K. In addition, the Mo-containing amorphous coating exhibited higher corrosion resistance than the Mo-free coating. The superior corrosion resistance can be attributed to the increased proportion of protective, stable Cr, Nb, and Mo oxides in the passive film and fewer defects of the Mo-containing coating. [ABSTRACT FROM AUTHOR]

To address the challenge of intelligently controlling air volume in regions affected by the frequent fluctuations in underground ventilation networks, a remote intelligent air regulation method based on machine learning was presented. This method encompasses three core components: local fan frequency conversion regulation, associated branch air resistance regulation, and a comprehensive integration of both. Leveraging foundational mine ventilation theory, the principles behind branch sensitivity air regulation were dissected. By applying these principles, the key performance indicators crucial for the regulation of air volume within the ventilation system were identified. Subsequently, an intelligent model for regional air volume control was constructed. To validate the approach, an experimental platform for intelligent air volume control was established, guided by geometric, dynamic, and kinematic similarity criteria. Then, the experimental methodologies for simulating various ventilation scenarios were discussed, the data acquisition techniques were introduced, and the obtained results were analyzed. Employing machine learning techniques, we utilized five distinct algorithms to predict the operational parameters of targeted air volume ventilation equipment. It enabled precise and efficient control of air volume within the region. The results indicated that the least squares support vector machine (LS-SVM) stood out by delivering high-precision predictions of target air volume ventilation equipment parameters, all while maintaining a relatively short calculation time. This swift generation of feedback data and corresponding air volume control strategies will contribute to the precise management of air volume in the area. This work served as a valuable theoretical and practical guide for intelligent mining ventilation control. [ABSTRACT FROM AUTHOR]

Gravitational bullet injuries, prevalent in the Middle East, particularly in Iraq, are a critical public health concern, often resulting from celebratory gunfire. In our Neurosurgery Teaching Hospital in Baghdad, we've observed that these injuries differ significantly from high-velocity gunshot wounds, characterized by lower velocity and energy due to air resistance and gravity. Unlike high-velocity bullets, gravitational bullets cause less bone fragmentation and radial brain damage. These bullets often end up on the tentorium or within the skull base, rarely transgressing the cerebellar tentorium on a vertical trajectory. We've also noticed that the pediatric population, particularly younger children, are more susceptible to these injuries due to their thinner cranial vertex, leading to more penetrating injuries and aggressive brain bleeding. Our observations underline the need for focused studies, awareness, regulation, and tailored management strategies to combat this overlooked issue. [ABSTRACT FROM AUTHOR]

The results of the analysis of the influence of the aerodynamic characteristics of the road train on its fuel efficiency are presented. Based on the analysis of known studies, the power balance equation and the known equation of road fuel consumption, it is shown that air resistance has a significant effect on fuel economy indicators. Through the analysis of the air resistance equation and taking into account known studies, it was concluded that one of the key parameters that affect the aerodynamics of the road train is the distance between the cab and the semi-trailer. The results of computer modeling of the aerodynamics of a two-track road train are presented. Based on the proposed model, it is shown that the distance between the cabin and the semi-trailer has a non-linear effect on the total air resistance expressed through the reduced pressure. On the basis of this, an assumption was made about the possibility of optimizing the specified distance according to the criterion of minimum air resistance. It has been established that the use of such technologies as aerodynamic panels can significantly improve the aerodynamic characteristics of a road train, which, in turn, will have a positive effect on fuel economy and other operational characteristics of the road train. A real example of how a decrease in the coefficient of ease of movement, which also takes into account air resistance, affects fuel consumption. It is shown that a decrease in the coefficient of ease of movement by only 0.04 units leads to a decrease in fuel consumption by 11%. It was concluded that the influence of the geometry of the road train, namely the distance between the cab and the semi-trailer, on the indicators of aerodynamics and fuel efficiency requires further research both by computer modeling and by researching physical models of road trains in a wind tunnel.